Conventionally, eyewear such as corrective glasses, protection glasses, sunglasses, and goggles include a lens and a frame. In such eyewear, frames are formed from, for example, metal materials such as pure titanium, nickel-titanium alloys, aluminum, magnesium, and gold; synthetic resin materials such as celluloid, acetate, and polyamide resin; and natural materials such as tortoiseshell.
Meanwhile, there are demands for improvements in mechanical properties (mechanical strength, etc.) and processability for eyewear. Thus, use of polyurethane elastomers having excellent mechanical properties and processability as an eyewear material have been examined.
To be more specific, for example, Patent Document 1 has proposed use of hard thermoplastic polyurethane produced by reacting diisocyanate including bis(isocyanatomethyl) cyclohexane and diol including cyclohexanedimethanol as an eyewear frame.
Furthermore, Patent Document 2 has proposed using, for example, when producing a spectacle frame using thermoplastic polyurethane resin, a thermoplastic polyurethane resin having a difference between the crystallization peak temperature and the glass transition temperature observed in DSC (derivative scanning calorimeter) analysis of 27° C. or more, and having a Shore D hardness of 74 or more.